Presented
at the International Test Conference - October 1996

Dr. Edward P. Sayre, P.E.

Abstract

This paper is a unique documentation of a MCM thermal
failure due to inadequate signal integrity of the test fixture used for
at-speed testing. An accurate SPICE model of the test fixture and MCM was
developed utilizing TDR techniques and analytical representations of the
test fixture elements. The SPICE analysis showed clearly that impedance
mismatches within the fixture components and MCM carrier and test socket
caused a significant increase in the RMS driver current and produced a 33%
increase in power dissipation in each MCM I/O driver. The additional
dissipation, in conjunction with the elevated temperature test environment,
caused the thermal failures observed during at-speed testing.

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